Keeping yourself and your class on track timewise can be a challenge. I talked about Harmony Hollow's Cool Timer in this blog post, but I just learned about another one.
Online Stopwatch is exactly that, an online stopwatch. You can count down or count up with it. It is simple to use, free, and easy to read. This is a great way to keep time in your class without having to purchase a stopwatch. You can even use a projector to have this up on the screen so that your students can keep an eye on their time.